It's been a couple of years now since Sabriena got a laptop and we connected the desktop to the TV to allow Duncan to play on it, almost completely on his own (we rarely use it these days). In the early days, he'd use an Xbox 360 controller, sitting back on the couch or the beanbag and enjoying his minecraft - but these days he's started using the mouse/keyboard more often, including using the desktop for YouTube instead of the PS4 as well.
We bought him a little chair, but it's still horrifically bad ergonomics for him, so we decided on Sunday that when the local opp shops opened on Monday, we'd take a look for a desk. We found not only a very cheap desk, but also an old office chair as well and so we set him up in the corner.
It means we've lost a few things - the corner where the desk set up, an ethernet cable won't reach (without feeding it behind the heater, and I'm not sure if that's safe). We don't have a TV-watching machine any more either.
But it's all worth it, because he's sitting up straight and is actually progressing towards learning how to type, and has only plugged the controller in once (it's better for Lego Worlds in many ways).